Truth may be stranger than fiction, but it is practically unrecognisable in Bart Layton's astonishing debut documentary. Mixing interviews with stylised dramatic reconstruction, Layton recounts the bizarre story of Frederic Bourdin, a 23 year old Frenchman living in Spain who in 1997 convinced a Texan family - plus the Spanish and US government - that he was their son who went missing three years earlier. Fascinating and disturbing, you literally won't believe your eyes.
Great documentaries are those that shake the structure and order of everyday life to the ground.
The all-American family accused of child sex crimes in Capturing the Friedmans. The investigation that uncovered a travesty of justice in The Thin Blue Line. A taxi driver's descent into the Orwellian Hell of Abu Ghraib in Taxi To The Dark Side.
And now The Imposter and the troubling, mercurial, charming and contemptible figure of Frederic Bourdin.
A damaged fantasist in fixed arrested development, director Layton allows Bourdin free rein to recount the events that saw him assume the identity of missing teenager Nicholas Barclay... despite the fact that Barclay vanished in Texas, USA and Bourdin was picked up by the authorities in Spain and bore no resemblance to the boy.
What becomes stranger still is that Barclay's family accepts without question that their blonde haired, blue eyed boy has reappeared thousands of miles across the globe with a radical change in appearance: mixed race complexion, different eye colour, thick French accent, five o'clock shadow.
Explaining in interview, they put this down to years of sexual abuse at the hands of a military-led child sex ring that Bourdin has invented.
This unbelievable blend of confidence trickery and seemingly wilful blindness is what fascinates most in The Imposter, and raises more tantalising and disturbing questions.
Is the family's obtuseness the result of guilt? They admit that they and Nicholas (who his sister describes as "no angel") had fought before he disappeared. Or is it simple grief that allowed them to believe this was their boy and find closure? Or something more sinister as Bourdin posits and private investigator Charlie Parker (larger than life and straight out of a Jim Thompson novel) attempts to prove... with the help of ears?
In the spirit of Oscar-winning documentarian Errol Morris, Layton uses inventive re-enactments with lookalike actors to present various versions of the "truth", even winding the film back early on to present the beginning from a different angle. This docu-drama approach fits the tone of Bourdin's recounting, the unrepentant conman describing events like the plot of a barmy movie.
Layton uses what little real footage exists for maximum effect, particularly unforgettable video of "Nicholas" being reunited with his family where the line between deception and self-deception is all but erased.
In a story this open-ended those wanting a tidy resolution will be left disappointed. But, late revelations and closing onscreen captions leave the impression this is a story whose truth lies between the cracks of everything you've just seen and heard.